1© 2009 Autodesk Sculpting with CVs 3D Model Control Vertices (CVs) are used to accurately describe a design as a 3D model. Control of CVs Similar expertise and fluency in sculpting with CVs will give full control over a design developed in 3D. 2D Drawing Sketched curves are used to describe a design in a 2D drawing. Control of the Pencil Expertise and fluency in sketching is essential to a designer.

2© 2009 Autodesk Shapes and Smoothness For Smoothness For industrial design, you will typically be aiming for smooth, clean curves and surfaces. Fewer CVs will create a smoother curve/surface. A single-span curve/surface will be the smoothest. For Complexity To trace out the shape of this character’s ear, you will need many CVs and many spans to get the ‘crinkly’ style of the shape.

3© 2009 Autodesk Number of CVs: Controlled by Degree and Spans Number of CVs = Degree + Number of Spans Number of CVs = Degree + Number of Spans Your choice: Change Degree orChange Number of Spans

4© 2009 Autodesk Spans Edit Point Single-Span Curve An Edit Point exists at the beginning and end of a simple curve and defines a ‘span’. Multi-Span Curve A multi-span curve joins single curve segments together at edit points (or ‘knots’). Each edit point connection is smooth but not as smooth as a single-span.

5© 2009 Autodesk Spans and Smoothness Single-Span Curve Will always be smooth Multi-Span Curve Is less smooth at the edit points Locators>Curve Curvature Shows a graphical plot of the curvature values. Open the option box to adjust what is displayed. Curvature = 1/Radius

6© 2009 Autodesk Degree Single-Span, Degree 1 = 2 CVs Single-Span, Degree 2 = 3 CVs Single-Span, Degree 3 = 4 CVs Single-Span, Degree 4 = 5 CVs Single-Span, Degree 5 = 6 CVs Single-Span, Degree 6 = 7 CVs Single-Span, Degree 7 = 8 CVs Degree is a mathematical property of a curve or of a surface dimension that controls how many CVs are available for modeling. Number of CVs = Degree + Number of Spans

7© 2009 Autodesk Degree and ‘Character’ Stiff, springy, pure curves Degree 2 and Degree 3 curves Fewer CVs Flowing, soft, complex curves Degree 5 and Degree 7 curves More CVs

8© 2009 Autodesk Setting Curve Degree New Curve You can set the degree of a curve before you create it by using the option window for the curve creation tools. Keypoint Arcs All the keypoint arc tools have the option to set the degree of curve created. Note that accuracy may be affected by choosing a low degree. Changing Degree The Control Panel can be used to change the degree of a curve. If the degree increases, the curve shape will be the same. If it decreases, the curve shape may alter.

9© 2009 Autodesk Setting Surface Degree Surface Tools If a surface is created by a surface tool, such as Revolve or Skin, the surface will take on the degree and number of spans of the curves used to define it. Control Panel You can change the degree or number of spans in a surface in the Control Panel in both the U and V directions. If the surface has a history relationship with a curve, this will be broken. Surface Primitives Each primitive has an option window where you can choose between degree 1 and 3. The default is degree 3. U V

10© 2009 Autodesk Creating Smooth Curves Two Ways to Create NURBS Curves Place 4+ CV points Place 2+ edit points Recommended Workflow Create a single-span curve by placing two edit points. Then pick and move CVs until you achieve the shape you want.

11© 2009 Autodesk Exercises EX1-Curves-degree.wire EX2-Circle-degree.wire EX3-Car-curves.wire EX4-Rotate-cvs-finger.wire

12© 2009 Autodesk Tools for Curves and Surfaces Attach Joins curves or surfaces. Only use the ‘Blend’ option, and be aware the shape of the curves or surfaces will change. Detach Splits curves or surfaces. Use the Ctrl key to snap to an isoparm. Use the Alt key to snap half-way between isoparms. Detaching Periodics Cylinders, spheres, and circles will need to be detached twice.

13© 2009 Autodesk Tools for Curves and Surfaces Extend Extends a curve or surface without modifying the original shape. Insert Inserts a new isoparm and hence a new span. Choose the direction (U or V) of insertion by selecting an isoparm in the right direction. Offset Offsets a curve or surface. Complex shapes may get distorted if the offset is too large.

14© 2009 Autodesk Tools for Working with CVs Pick>Hull Pick>Hull is a quick way to select a whole row of CVs. To maintain discipline in the shape you are sculpting, it is often useful to work with rows of CVs and transform them in a controlled way. This is particularly useful when working in the perspective window. Click on the hull line, not on a CV. Pick Walk Whether you have a CV or a Hull selected, the ‘pick walk’ will step along the CVs in the U or V direction. Nudge When using Transform>Move, the arrow keys will move by one screen pixel. If you zoom in, then the movement will be finer.

15© 2009 Autodesk Tools for Working with CVs Control Panel Transparency Reduce the brightness of the CVs and hulls to view the model more easily. ‘Xray’ Vision Allows all CVs and other controls to be seen through a shaded model.

16© 2009 Autodesk Working Symmetrically Controlling Symmetry ‘By Hand’ A sign of a skilled Alias modeler is being able to control CVs symmetrically using the mouse buttons and Transform tools. Snap to convenient grid points. Constrain moving and scaling to maintain symmetry. Even though it seems sensible to model only one half of a symmetrical surface, you will often get a smoother result across the center-line if you create a single curve or surface.

17© 2009 Autodesk ‘Automatic’ CV Symmetry Object Edit>Symmetric Modeling New in Alias 2010, the Symmetric Modeling tool is designed specifically to help maintain exact symmetry when you are CV sculpting a curve or surface that crosses the center-line. This tool makes the selected geometry symmetric and lets you modify the controls (CVs, edit points, blend points) on one side, while the corresponding controls on the symmetric half update automatically to maintain the symmetry. The symmetry plane is defined by the default symmetry plane for the layer that the curve or surface belongs to (Y=0 by default). This plane can be modified by using Layers>Symmetry>Set Plane.

18© 2009 Autodesk Advanced Tools for Working with CVs Control Panel: Move>CV The Move>CV tool on the Control Panel is designed for advanced surface sculpting. It offers very fine control when moving CVs or hulls. XYZ mode In XYZ mode, it is almost the same as using Transform>Move. The advantage is that you can set the step size, so that your mouse movement results in very fine movements of the CVs. NUV mode The ‘N’ in NUV refers to the normal direction of the surface. Moving in this direction means moving in and out from the surface, which can be more instinctive than an XYZ movement. X YZ N UV

19© 2009 Autodesk Duplicate Instance Edit>Duplicate>Object (Instance) Create related copies: Copy - another sphere node is simply created Instance - the same CV geometry is used in two (or more) locations Copy and Instance only work if you pick and move CVs—not Objects.

20© 2009 Autodesk Techniques: Speed Example Marking Menus Example Hotkeys Object Display> Control

21© 2009 Autodesk Extreme Examples of NURBS Sculpting

22© 2009 Autodesk Exercises EX5-Car-surfaces.wire EX6-Corkscrew.wire EX7-Detach-periodic.wire EX8-Jug-spout.wire EX9-Symmetric-Modelling.wire

23© 2009 Autodesk Projects P1-Cube-phone-form.wire P2-Soft-phone-form.wire P3-Juicer.wire P4-Car-degree.wire P5-Car-handle-recess.wire P6-Instances.wire